Acute and chronic postsurgical pain (CPSP) are a major health concern across the lifespan. Adolescents undergoing invasive musculoskeletal surgeries are particularly at risk, with 20% developing CPSP and associated deterioration in health-related quality of life (HRQL). Further, neurobiological and psychosocial changes during adolescence increase vulnerability to addiction, placing these youth at elevated risk for developing persistent opioid use following surgery. Despite research demonstrating the importance of psychological factors in persistence of pain and opioid use following surgery, standard perioperative care in youth relies on opioids to treat pain. Non-pharmacological interventions are not accessible or widely used in this population. Our own studies demonstrate efficacy of mHealth psychosocial interventions to improve chronic pain-related outcomes in youth. Other published data support efficacy of psychosocial interventions to reduce acute postsurgical pain in adolescents. Using stakeholder input, our team adapted our highly successful technology-delivered pain self-management intervention for the perioperative period in a program called SurgeryPal. We developed two distinct interventions to be delivered during 1) the pre-operative phase to target psychosocial risk factors, and 2) the post-operative phase to teach pain self-management skills. The goal of this proposal is to establish the effectiveness of our mHealth perioperative psychosocial intervention to improve clinically meaningful outcomes in adolescents undergoing major musculoskeletal surgery, and to identify the optimal timing of intervention delivery. During the UG3, our team will work cooperatively with the HEAL ERN Program to plan for the efficient implementation of our proposed multi-site randomized clinical trial at 25 collaborating centers and will ready our interventions for deployment. During the UH3 phase, we will conduct a randomized controlled trial in 500 youth age 12-18 years undergoing spinal fusion surgery and their parents. In addition to standard perioperative care, participants will be randomized using a factorial design to receive psychosocial intervention (SurgeryPal) or education (attention control condition) at two treatment phases, each of 4-weeks duration (pre-operative and post-operative) to test timing of intervention delivery. Primary study outcomes are acute pain severity and interference assessed over the first 2 weeks after surgery, and chronic pain intensity and interference at 3-month follow-up. Secondary outcomes include HRQL, psychosocial distress, sleep disturbance, and opioid use and misuse. We will examine synergy of psychosocial intervention during both treatment phases, and explore underlying treatment mechanisms of prevention of transition from acute to CPSP over 6 months. This project represents a significant advance in innovative approaches to deliver non-pharmacological therapies to youth undergoing major musculoskeletal surgeries, which may effect a paradigm shift in clinical practice. This intervention has potential to be integrated into pediatric surgery programs across the country to reduce incidence of CPSP and potential for addiction.